It was all about greed. Six people were killed and 13 others injured when a building in downtown Philly was being demolished earlier this year. District Attorney Seth Williams alleges contractor Griffin Campbell ignored safety rules so he could profit by selling joists and other dismantled parts of the four-story building. Williams said several construction and demolition experts testified before a grand jury that the structure should have been taken down brick by brick, by hand. Authorities maintain that Campbell removed key structural parts of the building with heavy machinery, which left the walls without support. The case prompted city leaders to issue new guidelines for demolitions.